A. Field of the Invention
The present invention relates to a clutch apparatus for use in motorized vehicles, the clutch apparatus having a unique configuration which allows for ease of disassembly, the clutch apparatus being provided with a vibration dampening mechanism that includes an undulated spring and the clutch apparatus having a minimal axial thickness.
B. Description of the Related Art
A typical clutch apparatus includes a flywheel fixed to a crankshaft of an engine, a clutch cover assembly fixed to the flywheel, and a clutch disc disposed between the flywheel and the clutch cover assembly, the clutch disc being connected to an input shaft of a transmission. The clutch cover assembly includes a dish-like clutch cover, a pressure plate covered by the clutch cover and opposed to the flywheel, and a diaphragm spring supported by the clutch cover for biasing the pressure plate toward the flywheel. The clutch disk is disposed between the flywheel and the pressure plate. When a release device axially moves the diaphragm spring, a biasing force against the pressure plate is released, and the pressure plate moves away from the clutch disk.
The clutch apparatus is such that the clutch disc is not provided with a damper mechanism, and the flywheel is made up of several members or portions, between which a damper mechanism is arranged. In accordance with this structure, the flywheel includes an input part and an output part, where the output part is opposed to the input part with a damper mechanism therebetween. The flywheel is such that it has an increased moment of inertia, so that a resonance frequency of the clutch apparatus is lower that an idling rotation speed of the engine.
The above described clutch apparatus has several drawbacks, one being its axial thickness. The configuration of the apparatus is such that its axial length is prohibitively greater that a clutch apparatus configured with a damper mechanism within the clutch disc instead of within the flywheel. It is desirable to minimize the axial dimensions of a clutch apparatus for use in small motorized vehicles and in front wheel drive vehicles where the motor is transverse mounted within the engine compartment of the vehicle.
In another clutch apparatus, a flywheel may include several elements such as a plate member having a thin axial thickness. An inertia member is fixed to an outer peripheral portion of the plate member for increasing the moment of inertia to a desirable level. Further, the inertia member may have an axially elongated structure for preventing radial protrusion. Another portion of the flywheel may include seats or mounts for the connection with the clutch cover, so that the inertial member is arranged radially outside the seats. This results in increase in the overall radial dimensions of the clutch apparatus.
Another flywheel configuration is not provided with a clutch cover seat, and instead the clutch cover is rigidly fixed to an outer peripheral portion of the flywheel by caulking, welding or shrink fitting. Elimination of the clutch cover seats reduces the whole radial dimension of the clutch apparatus. However, in such an arrangement, when the clutch disc in the clutch apparatus is worn and must be renewed due to wear or abrasion, the entire clutch apparatus must first be removed from the crankshaft before the clutch apparatus can be disassembled. Further, to disassemble the clutch apparatus, the caulking, welding must be removed or cut first, or the apparatus must be heated if assembled using a shrink fitting method. In this case, reuse of the disassembled clutch cover may be impossible and the clutch cover must be replaced with the clutch disc.
Another aspect of the clutch apparatuses described above is that a plurality of strap plates are typically used to secure an outer peripheral portion of the pressure plate to the clutch cover. The strap plates are provided for ensuring that the pressure plate rotates together with the clutch cover. In the conventional clutch cover assembly, the clutch cover is provided at its outer peripheral portions with recesses for disposing the strap plates at circumferentially equally spaced three positions. These recesses reduce a strength of the clutch cover.